Why did many notherners begin to oppose the civil war?

Many Northerners began to oppose the Civil War as the conflict dragged on and the human and economic costs escalated. The high casualty rates and destruction led some to question the war's objectives and whether the fight was worth the sacrifices being made. Additionally, the growing anti-war sentiment was fueled by the perception that the war was increasingly about preserving the Union rather than abolishing slavery, leading some to call for negotiation and peace rather than continued conflict.